ISC Risk Management Practice Question
You are analyzing a proprietary SCADA system's threat landscape. The system uses a non-standard protocol that prevents the use of traditional deep packet inspection (DPI) tools. Which method provides the most effective risk reduction?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enforce physical network isolation using unidirectional security gateways to separate the control network from the enterprise network.
When protocol-specific inspection is impossible, network segmentation and the implementation of unidirectional security gateways (data diodes) provide the highest assurance of protecting critical control systems from external threat vectors.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enforce physical network isolation using unidirectional security gateways to separate the control network from the enterprise network.
Why this is correct
Data diodes physically prevent data ingress, effectively mitigating network-based threats when DPI is not an option.
- ✗
Replace the proprietary protocol with OPC-UA to enable standard security monitoring.
Why it's wrong here
Replacing core SCADA protocols is often operationally impossible or dangerous in mission-critical environments.
- ✗
Implement a host-based firewall on the SCADA master station.
Why it's wrong here
Host-based firewalls do not protect against network-level protocol exploitation or lateral movement.
- ✗
Deploy an intrusion detection system (IDS) that uses behavioral pattern matching.
Why it's wrong here
Without DPI support for the proprietary protocol, standard behavioral IDS will likely fail to identify malicious payloads.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official (ISC)² exam blueprint
This ISC practice question is part of Courseiva's free (ISC)² certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ISC exam.